1. Field of the Invention
The invention relates to the field of collision avoidance systems, and, more particularly, to collision avoidance systems utilizing proximity radar on a vehicle and vehicle location radar located at blind intersections to prevent collisions.
2. Description of Related Art
The driver of an automobile is often deprived of information that would enhance his ability to operate the vehicle safely. Information concerning other vehicles in the immediate vicinity, which are those most relevant to the driver, is gleaned by visual inspection of those vehicles. Mirrors provide a means to locate and view vehicles behind and beside the driver's vehicle, but the view is obstructed by "blind-spots" and certain optical qualities of mirrors make other vehicles appear to be farther away then they actually are. The driver is able to gather even less information during poor weather conditions and during the night. Blind intersections, as the name implies, provide no information to the driver about approaching vehicles.
Moving map displays, common in rental automobiles in conjunction with global positioning satellite receivers, provide information to the driver about his location or about his location relative to his destination. In addition to helping the driver navigate, the information content of the display adds to the driver's ability to safely operate the vehicle. For example, the display allows the driver to plan lane changes in advance which helps prevent rapid, and sometimes reckless, lane changes in order to reach a desired exit ramp.
A type of radar termed micropower impulse radar or MIR, is known in the art. The radar is described in an article entitled "Radar on a Chip 101 Uses in Your Life: in the March 1995, issue of Popular Science. This publication is herein incorporated by reference and the radar unit is available commercially, e.g., Radio Shack retail stores.
The MIR is also discussed in an article at http://www-lasers.llne.gov/lasers/idp/mir/overview.html, the website for Lawrence Livermore National Laboratories, which is hereby incorporated by reference.
The micropower impulse radar (MIR) is a fundamentally different type of radar that was invented at Lawrence Livermore National Laboratory. It is a pulse radar, like other wide ultra-wide band radars, but it emits much shorter pulses than most and, it is built out of a small number of common electronic components, it is compact and inexpensive.
One unique feature of the MIR is the pulse generation circuitry, which, while small and inexpensive, has never before been considered in radar applications. Each pulse is less than a billionth of a second and each MIR emits about 2 million of these pulses per second. Actual pulse repetition rates are coded with random noise to reduce possibility of interference from other radars, while each is tend to itself. The same pulse is used for transmitting to send via the transmit as for sampling the receive signal.
Three direct advantages of the short pulse-width are:
1. The pulse is short, the MIR operates across a wider band of frequencies on a conventional radar, giving high resolution and accuracy, but almost making it less susceptible to interference from other radars. PA1 2. Since current is only drawn during this short pulse time and the pulses are infrequent, there are extremely low power requirements. One type of MIR unit can operate for years on a single AA battery. PA1 3. The microwaves emitted by the pulse are at exceedingly low and therefore mechanically safe levels (microwatts). Indeed, the MIR emits less than one millionth of the energy of the cellular telephone. An MIR radar can utilize range gating to selectively include or exclude signals from certain range intervals.
Currently, automobile occupants are limited in their ability to communicate with the occupants of other vehicles. Certain international signs and signals for happiness and displeasure can be issued, but conversation is only possible via CB or ham radio, both in use by limited, well-defined populations.
Global positioning satellite (GPS) receivers are known that can provide accurate information about the geographic location of the receiver and, by extension, the location of an object containing a GPS receiver.
Computational techniques are known that allow the determination of speed, acceleration, and direction of a moving GPS receiver that are based upon time interval interpretation of the GPS receiver's data points.
Radio broadcast of digital data is known. Self organizing communications protocols are known and were designed to assure accurate transmission of digital data even though there may be contention for a particular frequency. Such a protocol is preferably a carrier sense multiple access/collision detection (CSMA/CD) protocol.
Eyetracking devices are known particularly in conjunction with heads up displays in certain control applications in aircraft. An eyetracker device monitors the eyes of a user and calculates the direction in which the user is looking and, in some applications, the particular point in three dimensional space on which the user's eyes focus.
One commercial eyetracker is the Dual-Purkinje-Image (DPI) Eyetracker, manufactured by Forward Optical Technologies, Inc. of El Cajon, Calif. It determines the direction of gaze over a large two dimensional visual field with great accuracy and without any attachments to the eye. It operates with infra-red light which is invisible to the subject and does not interfere with normal vision. The eyetracker has a pointing accuracy on the order of one minute of arc and response time on the order of one millisecond. One can utilize the DPI Eyetracker with an infra-red optometer to allow a continuous measure of eye focus, producing a three dimensional eyetracker.
Touch screen displays, where the user indicates his choice by touching it on the display screen, are known.